The present invention relates to a device for manufacturing especially reinforced concrete pipes within a vertical mold whereby within the longitudinal axis of the mold a counter-rotating compaction head is vertically positioned so as to be rotatable about and axially slidable along the longitudinal axis of the mold. The counter-rotating compaction head comprises a distributing head with distributing rollers which is rotatably driven by a first shaft and a smoothing piston with a smoothing mantle which is rotatably driven by a second shaft counter to the direction of rotation of the distributing head.
Known devices for manufacturing reinforced concrete pipes with counter-rotating compaction heads are known from German Patent 27 38 944 and German Patent 35 30 953. These known devices are comprised of a vertically extending pipe mold and one or more counter-rotating compaction heads rotating about a common longitudinal axis. These counter-rotating compaction heads have two different portions for performing varying functions. The upper portion is in the form of a plate which is driven by a shaft and has at its upper sides rotatably supported pressing rollers for pressing the supplied material into the outer pipe mold. A smoothing cylinder, also called smoothing head or smoothing piston, with or without a second set of pressing rollers determines as the second element the exact inner diameter of the pipe to be produced and determines the surface quality of the inner pipe wall.
In this context it is necessary for achieving an effective manufacture to rotate the counter-rotating compaction head at a very fast rotational speed and also move it in a very short period of time over the entire length of the pipe to be manufactured, i.e., move the compaction head axially to and fro.
With the known devices the outer and/or inner surface quality of the manufactured pipes does not always correspond to the required specifications. Furthermore, especially for pipes with reinforcement, there is the risk involved that the adhesion between the reinforcement and the concrete is flawed and that so-called reinforcement shadows result, for example, due to distortion or warping of the reinforcement during manufacture. In another known device a core that extends over the entire length of the tube predetermines the inner tube diameter. After completion of the manufacturing process of the pipe the entire core (see German Patent 22 16 648) or the entire casing including core (German Patent 31 15 181) is vibrated by a support plate.
These known devices have the disadvantage that excessive vibration of the concrete may occur such that within the pipe so-called vibration nests are formed and separation of the concrete takes place. In order to prevent such excessive vibration, it is known (German Patent 40 22 089) not to centrally vibrate the core, but to partially vibrate the core with different vibrators. Such a method however requires a complex and complicated apparative design; furthermore, the construction of the core with a plurality of vibrators is very complicated.
It is therefore an object of the present invention to provide a device with which the disadvantages of the known devices can be overcome, which has a simple construction and with which especially reinforced concrete pipes can be manufactured in an economic manner with uniform, flawless compaction. The inventive device should furthermore be of a comparatively simple construction.